Metal safe stores whiskey (6)
I believe the answer is:
pewter
'metal' is the definition.
(pewter is a kind of metal)
'safe stores whiskey' is the wordplay.
'safe' becomes 'peter' (I've seen this before).
'stores' indicates putting letters inside.
'whiskey' becomes 'w' (alpha bravo charlie delta ...).
'peter' placed around 'w' is 'PEWTER'.
(Other definitions for pewter that I've seen before include "Alloy of tin with copper and antimony" , "Grey alloy of tin and lead, makes mugs etc." , "Tin alloy used in tankards, etc" , "prize-money" , "Plate" .)